Hydrodynamic, mechanical multi-speed compound transmission

Details Hydrodynamic, mechanical multi-speed compound transmission Hydrodynamic, mechanical multi-speed compound transmission

2000-12-07

2004-02-03

Lewis, Trisha D (Department: 3681)

Planetary gear transmission systems or components

Fluid drive or control of planetary gearing

Single impeller-turbine type fluid circuit divides or...

C475S043000, C475S044000

Reexamination Certificate

active

06685593

ABSTRACT:

The invention concerns a hydrodynamic mechanical multi-speed compound transmission.
Hydrodynamic mechanical multi-speed compound transmissions, consisting of a hydrodynamic speed/torque converter and a mechanical transmission part, are known in a variety of types. The publication DE 38 04 393 C2 identifies a hydrodynamic multi-speed compound transmission, consisting of a torque converter and a gearbox in series. The gearbox contains two planetary gear trains, where the planet carriers of both planetary gear trains are mutually linked and form the output side of the gearbox. The number of required planetary gear members or planetary gear trains (possibly a Ravigneaux set) may be minimized with such an arrangement, and with an appropriate allocation of gears at least three gear levels can be obtained, which are minimized in length, seen in an axial direction. The hydrodynamic speed/torque converter contains an impeller, a turbine wheel and two stators (a first stator and a second stator) where means are designed to enable the linkage of the turbine wheel and the first stator with the mechanical gears by means of a gearbox. In particular, the overall gearbox input shaft may be linked either with the hydrodynamic speed/torque converter and thus via the turbine wheel with the sun gear of one planetary gear train of the mechanical gear part or directly via a so-called bypass clutch with the same. The first stator is linked via a free-wheel with the sun gear of the second planetary gear train of the mechanical gear part. The characteristics of the hydrodynamic speed/torque converter across the whole range of gear ratios and the gear ratio of the mechanical gearbox are modified by switching the path of transmission of the moment emanating from the first stator shaft, namely by the optional use of linkage and/or brake arrangements, which enable either a lock of the first stator shaft or a linkage of the first stator shaft with the turbine wheel shaft and thus with the first sun gear of the first planetary gear train.
The disadvantage of the transmission described in the publication referenced above consists of the relatively high construction requirement, which increases costs, caused among other reasons by the use of a single level, three phase converter and the availability of support for both of its stators. This transmission yielded good results in the low speed range and the potential low speed range conversion, but some improvements are still required in certain uses.
The publication JP 09079346 A contains an example of a hydrodynamic-mechanical multi-speed compound transmission to provide for five gear levels. This contains a hydrodynamic transmission part in the form of a hydrodynamic speed/torque converter with an impeller, a turbine wheel, a stator located between these two and a gearbox switched in series with them. The gearbox likewise contains two planetary gear trains, where the planet carriers of both planetary gear trains are linked with each other and form the output side of the gearbox. The stator is linked to the planetary gear trains via a freewheel. In order to realize the fourth and fifth gears, a speed/torque converter unit in the form of a planetary gear train is integrated between the turbine wheel and the two planetary gear trains of the mechanical gearbox, which converts the moment of the turbine by a gear to the two planetary gear trains. As used in vehicles, the power transfer via the hydrodynamic speed/torque converter is used only during the low speed range and to a certain extent in the first lower gear. In the remainder of the useable range, the power transfer bypasses the hydrodynamic speed/torque converter, usually by means of a bypass clutch. Of significance for the use of a hydrodynamic speed/torque converter during the low speed range are the following advantages of hydrodynamic power transfer: continuous, with torque conversion, elastic, frictionless and vibration-reducing. Specific requirements are imposed on the transfer process in its linkage with motors for various uses during the low speed range. For use in vehicles, a particular behavior, specifically a particular power transfer by the impeller of the hydrodynamic speed/torque converter is desirable. By means of the linkage between the stator of the hydrodynamic speed/torque converter and the planetary gear trains connected by their shafts, the stator will in certain conditions be impelled in the opposite direction between impeller and turbine wheel. While this solution provides a feasible method to supply several gear speeds in a compact size and simultaneously an improved transfer during the low speed range with a particularly improved conversion during acceleration and improved efficiency, this generally does not suffice to meet all requirements of use. Likewise, the linkage of the additional planetary gear train is cumbersome to design and must be considered during design of the gearbox. Particularly if standard speed/torque converter units are used, the placement or linkage of the additional planetary gear train can be difficult.
Thus, the invention is targeted to a further development of the type of transmission described above, so that it may satisfy the existing use requirements, particularly during the low speed range, while maintaining the advantage of low weight and small size. The transmission is intended specifically for use in the drive train of vehicles or other uses, where an essentially load-free ramping of the drive motor is desired in addition to the advantages of hydrodynamic power transfer. A further objective is the reduction of the construction resource requirements and the costs of the transmission.
The hydrodynamic-mechanical multi-speed compound transmission contains a first hydrodynamic transmission part and an additional second mechanical transmission part. The mechanical transmission part contains at least two planetary gear trains for the realization of at least three gear levels, a first planetary gear train and a second planetary gear train, which are designed and constructed in such a way that in each case one set of matching elements of the first planetary gear train and second planetary gear train can be linked at least indirectly with the transmission input shaft or with an element of the hydrodynamic speed/torque converter and where there is in addition a second set of matching elements, where an element of the first planetary gear train has a fixed linkage with an element of the second planetary gear train, and where this linkage forms the output of the mechanical speed/torque converter, which is linked at least indirectly with the output of the transmission. According to the invention, the hydrodynamic speed/torque converter of the first hydrodynamic transmission part is designed as a single-level two-phase hydrodynamic speed/torque converter. This includes an impeller, a turbine wheel and a stator. According to this embodiment, only a turbine level is included and the reaction member in the form of a stator rotates permanently or only intermittently. According to the invention, this is solved by connecting the stator via a geared member with a solid support or a freewheel with the first planetary gear train. According to the invention, the turbine wheel of the hydrodynamic speed/torque converter has a fixed linkage with the second planetary gear train, i.e. the linkage does no contain intervening or potentially intervening speed/torque converter units. Likewise, this embodiment reduces the power potentially transferred in the power train by an impeller through twist modification of the fluid flow at the flow from the stator to the impeller, particularly for use in vehicles in order to lower energy consumption of the motor in the low speed range for at least a portion of the low speed range. The twist modification is preferentially generated by powering the stator in the direction of rotation opposite to the rotation of the impeller and the turbine wheel. The resulting increase of conversion and improvement of the efficiency is increased by the absence

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